Causes

Insulin resistance. Most people who have acanthosis nigricans have also become resistant to insulin, a hormone secreted by the pancreas that allows your body to process sugar. Insulin resistance is what eventually causes type 2 diabetes.

Obesity. Most people who develop acanthosis nigricans are overweight or obese, which is a strong risk factor for developing insulin resistance.

Hormonal disorders. Acanthosis nigricans often occurs in people who have disorders such as ovarian cysts, underactive thyroids or problems with the adrenal glands.

Certain drugs. Medications such as oral contraceptives and corticosteroids, such as prednisone, may cause acanthosis nigricans — as can high doses of niacin.

Cancer. Acanthosis nigricans also sometimes occurs when a cancerous tumor begins growing in an internal organ, such as the stomach, colon or liver.

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